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Overdoor Heating

The vocabulary used to describe heaters designed to be installed over doors can be very confusing.  The terms air curtain, screen heater, overdoor heater etc. are bandied about and seem to mean completely different things to different people.

Our main purpose here is to differentiate between two products both which have a useful but distinctly different purpose.

Overdoor Heaters

Overdoor heaters are widely used in shops and can be wall-mounted, suspended or recessed into the ceiling above standard height doors.  They provide a warm welcome to customers and a localised boost to the air temperature, offsetting the heat loss associated with frequently opening doors.  BN Thermic’s 800 Series is ideal for this application.  The 800 Series extends from a 3kW model best suited to a single door to 6kW and 9kW models for wider entrances. 

All 800 series heaters come with a bracket for wall-mounting and also have threaded holes for drop rod suspension where this installation method is preferred.  A remote mounted control box provides on/off/high heat/low heat/fan only settings.

>>Full details of BN Thermic’s 800 Series Air Curtains

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Air Curtains

Air curtains are mounted above doorways and produce a high velocity air stream creating an invisible barrier between indoor and outdoor environments.  Often used in stores with an open door policy, an air curtain will help reduce heating costs in winter and air conditioning costs in summer, without impeding foot traffic. An air curtain will also minimise the ingress of pollutants and insects

In cooler conditions, the ‘chill factor’ associated with a high velocity air stream can be uncomfortable and therefore  air curtains are usually fitted with electric heating elements which warm the airstream thereby offsetting the ‘chill factor’ and contributing to a building’s heating requirement.

The Air Curtain Range

BN Thermic offers two ranges of air curtains.  CA Commercial Air Curtains are best suited to applications such as larger shops/restaurants or businesses with a fairly open door policy. 

For large commercial premsies like DIY stores, hotel and leisure centres,  we would always recommend our HCA High Capacity Air Curtains. HCAs are all 3 phase and are suitable for higher mounting positions.

>> Full details of BN Thermic range of Commercial Air Curtains

>> Full details of BN Thermic range of High Velocity Air Curtains

(Please be aware that a high velocity air stream is inevitably accompanied by a noticeable noise output.  This fact must be taken into account, especially if people are working in close proximity to an entrance.)

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Selecting the Right Overdoor Heater or Air Curtain 

Selecting the right overdoor heater or air curtain is very important and can be tricky. For help with product selection, BN Thermic’s engineers are a call away. All they require is the width and height of your door and an idea of the environment the unit is going into.

Over Door Heater FAQs & Guide

  • An overdoor heater (often referred to as an over door heater or simply a door heater) is a linear fan heater positioned above a door.  It produces a relatively low velocity air stream that blows down across the doorway.  

    Electrically heated overdoor heaters (such as those manufactured by BN Thermic) incorporate electric heating elements which heat the moving air to a pleasantly warm temperature.

    Frequently used in shops, cafes and restaurants, overdoor heaters provide a warm welcome for customers and localised heating at a point of high heat loss.  Overdoor heaters also mitigate against cold draughts.

  • An air curtain is a linear device installed above a door.  Its primary function is to produce a stream of air across an open doorway creating an invisible barrier and, in doing so, limiting the loss of warm air.  

    Some air curtains offer no heating whatsoever and these are generally known as ambient air curtains.  However, an unheated, high velocity air stream induces a very noticeable cooling effect which can be uncomfortable for people in the vicinity.  For this reason, most air curtains are supplied with either built-in electric heating elements or hot water coils.

  • An overdoor heater (often referred to as an over door heater or simply a door heater) and an air curtain are similar in that they are both positioned above a door and produce a stream of air directed downwards towards the floor.

    The difference is the velocity of the air stream.  Overdoor heaters produce a relatively low velocity air stream when compared to a similarly sized air curtain.  The implications of this difference are as follows.

    • Comparing units with the same kW output, an overdoor heater will produce an air stream that feels warmer
    • An overdoor heater will be quieter than a similarly sized air curtain
    • An overdoor heater will not be as effective at producing an invisible barrier across an open doorway as an air curtain and, therefore, will not be as efficient in limiting the loss of warn air from a heated building
  • An air curtain reduces heating bills by creating an invisible air barrier across a doorway and preventing heated air from escaping.  Higher velocity air curtains will produce a more effective barrier and be suitable for a higher mounting position but will produce more noise than a lower velocity equivalent.  Higher velocity air curtains will also need a higher output heater to achieve an acceptable air stream temperature resulting in somewhat higher running costs.

    BN Thermic offers two types of air curtain.

    High capacity air curtains are ideally suited to larger commercial and industrial premises such as superstores and large-scale reception areas.

    Commercial air curtains are better suited to convenience stores, small-scale reception areas and lobbies etc.